Hardware » History » Version 9
Luiz Fernando Lavado Villa, 2019-02-28 14:43
1 | 1 | Luiz Fernando Lavado Villa | h1. Hardware |
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2 | 2 | Luiz Fernando Lavado Villa | |
3 | 4 | Luiz Fernando Lavado Villa | {{>toc}} |
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5 | 2 | Luiz Fernando Lavado Villa | The hardware of the single-phase project consists of a 10cm by 10cm printed circuit board that hosts 5 electronics blocks. |
6 | 3 | Luiz Fernando Lavado Villa | These blocks all fulfill functions which are necessary to the proper operation of any power electronics converter. |
7 | Figure 1 illustrates these blocks. |
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9 | 9 | Luiz Fernando Lavado Villa | p=. {{thumbnail(theory_power_converter_1.png, size=350, title=General overview of a power electronics converter)}} |
10 | _Figure 1 - General overview of a power electronics converter_ |
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11 | 1 | Luiz Fernando Lavado Villa | |
12 | 4 | Luiz Fernando Lavado Villa | Each block is explained in detail in the sections below. |
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14 | 4 | Luiz Fernando Lavado Villa | h2. Power Block |
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16 | 9 | Luiz Fernando Lavado Villa | To better explain the Power Block, this page splits its presentation in theory and practice. |
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18 | h3. Theory |
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20 | 5 | Luiz Fernando Lavado Villa | The Power Block is the part that manages input/output power within the board. |
21 | It consists of a single inverter leg, as illustrated in the figure below. |
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24 | 1 | Luiz Fernando Lavado Villa | p=. {{thumbnail(single_phase_topology.png, size=350, title=The power topology of the single-phase board)}} |
25 | 9 | Luiz Fernando Lavado Villa | _Figure 2 - The power topology of the single-phase board_ |
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27 | 9 | Luiz Fernando Lavado Villa | Figure 2 shows a Vlow, VHigh, T1, T2, D1, D2 and L. |
28 | Vlow is the low-side voltage, VHigh is the high-side voltage, T1 and T2 are two transistors, D1 and D2 are two diodes and L is an inductor. |
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31 | This topology is current bi-directional. |
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32 | This means that its input can be either on the high-side or on the low-side. |
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33 | If the input is on the high-side, the circuit acts as a buck or step-down converter. |
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34 | If the input is on the low-side, the circuit acts as a boost or step-up converter. |
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37 | 6 | Luiz Fernando Lavado Villa | This topology allows the control of the current in the inductor L by controlling its charge and discharge using the switches. |
38 | The figure below shows the switching and the current flow within the inductor. |
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40 | 1 | Luiz Fernando Lavado Villa | p=. {{thumbnail(states_converter_1.png, size=700, title=Current flow during switching)}} |
41 | 9 | Luiz Fernando Lavado Villa | _Figure 3 - The power topology of the single-phase board_ |
42 | 8 | Luiz Fernando Lavado Villa | |
43 | The switching leads to an average current flow between its input and output as shown in the image below. |
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45 | 1 | Luiz Fernando Lavado Villa | p=. {{thumbnail(switching_states_1.png, size=700, title=Current flow during switching)}} |
46 | 9 | Luiz Fernando Lavado Villa | _Figure 4 - Left: average current in the inductor increases_ |
47 | _Center: average current in the inductor stable_ |
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48 | _Right: average current in the inductor decreases_ |
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49 | 1 | Luiz Fernando Lavado Villa | |
50 | 9 | Luiz Fernando Lavado Villa | As figure 4 shows, the key to control the current in the power converter is to control the duration of the signal that is sent to the transistors. |
51 | This duration is called *duty cycle* . |
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52 | A longer duty cycle will lead to a increase in current, while a shorter duty cycle will lead to a decrease in current. |
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54 | The duty cycle is the single most important control variable in a power converter. |
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56 | The presentation above is, obviously, not complete since there are further phenomena to be taken into account. |
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57 | The instantaneous rise and fall in current will lead to abrupt variations in voltage at both the high and low sides. |
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58 | To filter these variations, power converters are equipped with capacitors in both sides, which effectively provide the instantaneous current needed by the converter. |
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60 | The relationship between high and low side voltages, high and low side currents, and the duty cycle is given by the equations below. |
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62 | * Boost mode |
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64 | p=. !http://www.codecogs.com/eq.latex?\dfrac{V_{High}}{V_{Low}}=\dfrac{I_{Low}}{I_{High}}=\dfrac{1}{1-D}! |
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66 | * Buck mode |
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69 | h3. Practice |
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78 | 4 | Luiz Fernando Lavado Villa | h2. Measurement Block |
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80 | h2. Control Block |
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82 | h2. Driver Block |
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84 | h2. Feeder Block |